<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
</head>
<body>
    <script>
        function getLong(r){
            var r =prompt('请输入圆的半径：');
            getLong = Math.PI * r * 2;   
            document.write('圆的周长为：' + getLong +'</br>')
        }getLong();
        function getArea(r){
            var r =prompt('请输入圆的半径：');
            getArea = Math.PI * r * r;  
            document.write('圆的面积为：' + getArea )
        }getArea();
    </script>
</body>
</html>